Voice coil motor coupling structure of hard disk drive

ABSTRACT

A voice coil motor coupling structure of a hard disk drive for coupling a voice coil motor to a base plate of the hard disk drive, the voice coil motor includes a coil coupled to a rear end portion of an actuator arm, an upper yoke and a lower yoke provided at upper and lower portions of the coil, respectively, separated at a predetermined distance from the coil, and a magnet attached to the lower surface of the upper yoke. The voice coil motor coupling structure includes a countersink formed in the lower yoke, a countersunk head screw inserted in the countersink and coupled to a screw coupling hole provided in the base plate to fix the lower yoke to the base plate, a boss insertion hole formed in each of the lower and upper yokes at both end portions in a lengthwise direction, a boss protruding from the base plate and inserted in each of the boss insertion holes to prevent horizontal movements of the lower yoke and the upper yoke, and a screw inserted in each of the boss insertion holes and coupled to a screw coupling hole provided at each boss to fixedly couple the upper yoke to the lower yoke. Thus, the lower yoke of the voice coil motor can be stably fixed at an accurate position not only on a flat type base plate but also on a bowl type base plate.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority of Korean Patent ApplicationNo. 2002-60525 filed on Oct. 4, 2002 in the Korean Intellectual PropertyOffice, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a hard disk drive, and moreparticularly, to a voice coil motor coupling structure of a hard diskdrive for coupling a voice coil motor which pivots an actuator to a baseplate.

[0004] 2. Description of the Related Art

[0005] Hard disk drives (HDDs) are auxiliary memory devices for acomputer which record and reproduce data on a magnetic disk using amagnetic head.

[0006]FIG. 1 is a plan view illustrating a conventional hard disk drive.FIG. 2 is a perspective view illustrating a conventional actuator and aconventional voice coil motor.

[0007] Referring to FIGS. 1 and 2, a conventional hard disk drivecomprises a magnetic disk (hard disk) 20 which is a recording mediumwhere data is recorded, a spindle motor 30 installed on a base plate 10and rotating the magnetic disk 20, and an actuator 40 having a magnetichead 41 to record data on the magnetic disk 20 and reproduce the datafrom the disk 20.

[0008] In general, one or more magnetic disks 20 separated at apredetermined distance from each other are installed to be rotated bythe spindle motor 30. On the disk 20, a parking zone 21 is provided atthe inner circumferential side of the disk 20 and a data zone 22 where amagnetic signal is recorded is provided outside the parking zone 21. Aslider 42 is disposed in the parking zone 21 when the power is turnedoff.

[0009] The actuator 40 is installed on the base plate 10 and pivotsaround a pivot shaft 47 provided on the base plate 10. The actuator 40has an arm 46 in which a pivot hole 48 is formed in the middle portionthereof so that the actuator 40 can be coupled to the pivot shaft 47. Asuspension 44 installed at one end portion of the arm is elasticallysupporting the slider 42 having the magnetic head 41 toward a surface ofthe magnetic disk 20.

[0010] The actuator 40 pivots by a voice coil motor (VCM) 50. The VCM 50has a coil 56 coupled to the other end portion of the arm 46. A loweryoke 51 is fixedly installed on the base plate 10 under the coil 56separated by a predetermined distance. An upper yoke 52 is installedabove the coil 56 and coupled to the lower yoke 51 by a screw 59.Magnets 53 and 54 are attached to the upper surface of the lower yoke 51and the lower surface of the upper yoke 52, respectively. The respectivemagnets 53 and 54 are separated a predetermined distance from the coil56.

[0011] An actuator locking apparatus is provided for locking theactuator 40 when the slider 42 is disposed in the parking zone 21 of themagnetic disk 20. The actuator locking apparatus comprises a metal piece63 installed at an end portion of the arm 46, a bending portion 66extending from an edge of the upper yoke 52 and bent downward andcontacting with the upper surface of the lower yoke 51, and a slot 67formed in the bending portion 66.

[0012]FIG. 3 is a side view illustrating a conventional voice coil motorcoupling structure. FIG. 4 is a perspective view illustrating a methodof coupling the conventional voice coil motor on the base plate. InFIGS. 1-4, the same reference numerals indicate the same elements havingthe same functions.

[0013] Referring to FIGS. 3 and 4, a boss 14 protrudes from the uppersurface of the base plate 10. The boss 14 is inserted in a bossinsertion hole 57 which is provided at one end portion of the lower yoke51. A screw insertion hole 58 into which a screw 59 is inserted isformed in the other end portion of the lower yoke 51. Additional screwinsertion holes 56 a and 56 b into which screws 59 are inserted areformed at both end portions of the upper yoke 52.

[0014] In the above coupling structure, in order to couple the voicecoil motor 50 to the base plate 10 the lower yoke 51 and the upper yoke52 are firmly coupled by a magnetic force of the magnets 53 and 54.While the lower yoke 51 and the upper yoke 52 are coupled, the boss 14formed on the base plate 10 is inserted into the boss insertion hole 57provided at one end portion of the lower yoke 51. Then, the lower yoke51 and the upper yoke 52 are rotated around the boss 14 to match thescrew insertion holes 58 and 56 b to a screw coupling hole 12 formed inthe base plate 10. The coil 56 coupled to a rear end portion of the arm46 is inserted between the two magnets 53 and 54. The lower yoke 51 andthe upper yoke 52 can be rotated since the upper surface of the baseplate 10 is flat. Then screws 59 are inserted into the screw insertionholes 56 a, 56 b, and 58 and coupled to the screw coupling holes 12, sothat the lower yoke 51 and the upper yoke 52 are fixedly installed onthe base plate 10.

[0015] In the conventional hard disk drives, a plurality of disks areinstalled to increase a data storage capacity. However, with a rapidincrease in surface recording density of a disk, one or two disks canstore a sufficient amount of data. In particular, hard disk drives usinga single disk in which data is recorded on only one side have beendeveloped. Since only one magnetic head and one arm is needed, hard diskdrives can be made narrower. In the conventional hard disk drives, avoice coil motor in which magnets are provided at the upper and lowersides of a coil is mainly used. However, in a case of an actuator havingonly one arm for a single disk, a voice coil motor requiring a singlemagnet installed only on one of the upper or lower sides of the coil maybe desired. Therefore, hard disk drives can be made narrower.

[0016] The type of the base plate has changed from a conventional flattype to a bowl type. When the base plate is made into a bowl type, sincea flat cover plate is coupled to the base plate by pressing, the costfor manufacturing may be reduced compared to that of the conventionalbowl type cover plate manufactured by aluminum die casting. Since thelower yoke and the upper yoke of the voice coil motor may interfere witha protruding side wall of the interior of the bowl type base plate, thevoice coil motor cannot be assembled in a state in which the lower yokeand the upper yoke of the voice coil motor are first coupled together.Thus, after the lower yoke is assembled to the base plate, the actuatorarm is assembled so that the rear end portion of the actuator arm towhich the coil is coupled is disposed above the lower yoke. Then, theupper yoke is coupled to the lower yoke. Since the lower yoke is notfirst stably fixed to the base plate, when the upper yoke is coupled tothe lower yoke, the lower yoke is moved horizontally and vertically bythe magnetic force of the magnet attached to the lower surface of theupper yoke, which makes it difficult to couple the voice coil motor.Therefore, a new voice coil motor coupling, structure is needed in thehard disk drive having the above structure.

SUMMARY OF THE INVENTION

[0017] Accordingly, it is an aspect of the present invention to providea voice coil motor coupling structure of a hard disk drive which enablesa stable and easy coupling of the lower yoke and the upper yoke of thevoice coil motor to the base plate.

[0018] Additional aspects and/or advantages of the invention will be setforth in part in the description which follows and, in part, will beobvious from the description, or may be learned by practice of theinvention.

[0019] The foregoing and/or other aspects of the present invention areachieved by providing a voice coil motor coupling structure of a harddisk drive for coupling a voice coil motor to a base plate of the harddisk drive wherein the voice coil motor comprises a coil coupled to arear end portion of an actuator arm, an upper yoke and a lower yokeprovided at upper and lower portions of the coil, respectively, at apredetermined distance from the coil, and a magnet attached to the lowersurface of the upper yoke, the voice coil motor coupling structurecomprises a countersink formed in the lower yoke, a countersunk headscrew inserted in the countersink and coupled to a screw coupling holeprovided in the base plate to fix the lower yoke to the base plate, bossinsertion holes formed in each of the lower and upper yokes respectivelyat both end portions in a lengthwise direction, bosses protruding fromthe base plate and inserted in the boss insertion holes to preventhorizontal movements of the lower yoke and the upper yoke, and screwsinserted in the boss insertion holes and coupled to respective screwcoupling holes provided at each boss, fixedly coupling the upper yoke tothe lower yoke.

[0020] The countersink is provided at a position corresponding to aneutral zone of the magnet.

[0021] When the countersunk head screw is inserted in the countersunk, ahead portion of the countersunk head screw does not protrude above theupper surface of the lower yoke.

[0022] The height of each boss is greater than that of the lower yokeand less than a sum of the heights of the lower yoke and the upper yoke.

[0023] A first support portion protruding to a predetermined height andhaving a diameter greater than that of a lower end portion of thecountersink is formed around the screw coupling hole provided in thebase plate, and a plurality of second support portions each protrudingto a predetermined height and having a diameter greater than that ofeach of the boss insertion holes is formed around a lower portion ofeach boss, so that the first and second support portions support thelower yoke to be separated a predetermined distance from the base plate.

[0024] Upper surfaces of the first and second support portions are flatand have the same height.

[0025] The contact portion provided on the lower yoke to lock theactuator and bent such that an upper surface of the contact portion islower than an upper surface of the lower yoke. A recess having apredetermined depth is formed in the base plate to avoid interferencewith the contact portion of the lower yoke.

[0026] Although the base plate is of a bowl type, the voice coil motorcoupling structure may be applied to a hard disk drive having a flattype base plate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] These and/or other aspects and advantages of the invention willbecome apparent and more readily appreciated from the followingdescription of the embodiments taken in conjunction with theaccompanying drawings in which:

[0028]FIG. 1 is a plan view illustrating a conventional hard disk drive;

[0029]FIG. 2 is an exploded perspective view illustrating a conventionalactuator and a conventional voice coil motor in FIG. 1;

[0030]FIG. 3 is a side view illustrating a portion of the voice coilmotor to show a conventional voice coil motor coupling structure;

[0031]FIG. 4 is a perspective view illustrating a method of coupling theconventional voice coil motor to the base plate;

[0032]FIG. 5 is an exploded perspective view illustrating a voice coilmotor coupling structure according to an embodiment of the presentinvention; and

[0033]FIG. 6 is a side view illustrating the voice coil motor of FIG. 5coupled to a base plate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] Reference will now be made in detail to the embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout. The embodiments are described below to explain the presentinvention by referring to the figures.

[0035] Referring to FIGS. 5 and 6, a hard disk drive includes anactuator 140 to move a magnetic head 141 for recording and reproductionof data to a predetermined position on a disk (not shown). The actuator140 includes an arm 146 installed on a base plate 110 capable ofpivoting. A pivot hole 148 is formed in a middle portion of the arm 146and a pivot shaft 147 installed on the base plate 110 is inserted intothe pivot hole 148. The magnetic head 141 is mounted on a slider 142 anda suspension 144 elastically supporting the slider 142 toward a surfaceof the disk is installed at one end portion of the arm 146.

[0036] A voice coil motor 150 pivoting the actuator 140 is installed inthe hard disk drive. The voice coil motor 150 comprises a coil 156coupled to the other end portion of the arm 146, a lower yoke 151installed under the coil 156 at a predetermined distance from the coil156, and an upper yoke 152 installed above the coil 156. A magnet 154 isattached to a lower surface of the upper yoke 152 at a predetermineddistance from the coil 156.

[0037] The voice coil motor 150 having the above structure andcontrolled by a servo control sys tem pivots the actuator 140 in adirection based on the direction of the current applied to the coil 156and the direction of a magnetic field generated by the magnet 154. Whenthe power of the hard disk drive is turned on and the disk starts torotate, the voice coil motor 150 moves the magnetic head 141 from aparking zone (not shown) to a data zone (not shown) of the disk. Incontrast, when the power of the hard disk drive is turned off and thedisk stops rotating, the voice coil motor 150 pivots the arm 146 to movethe magnetic head 141 from the data zone to the parking zone of thedisk.

[0038] The voice coil motor 150 of a one magnet type is installed on thebase plate 110. When the base plate 110 is a bowl type, the voice coilmotor 150 is installed as follows. First, the lower yoke 151 of thevoice coil motor 150 is fixed to the base plate 110. Next, the arm 146is assembled to the pivot shaft 147. Then, the upper yoke 152 is coupledto the lower yoke 151.

[0039] In order to install the voice coil motor 150 on the bowl typebase plate 110 in the above method, the following coupling structure isprovided.

[0040] A countersink 157 having an inclined angle of about 45° is formedin the lower yoke 151 of the voice coil motor 150. A screw coupling hole112 is provided at the base plate 110 at a position corresponding to thecountersink 157. A countersunk head screw 158 is inserted into thecountersink 157. As the countersunk head screw 158 is coupled to thescrew coupling hole 112, the lower yoke 151 is fixed to the base plate110. When the countersink 157 and the countersunk head screw 158 areused, the contact area increases, and the lower yoke 151 can be morefirmly fixed to the base plate 110. Also, since the lower yoke 151 isfirmly fixed to the base plate 110, when the upper yoke 152 is coupledto the lower yoke 151, the lower yoke is prevented from being moved by amagnetic force of the magnet 154 attached to the upper yoke 152.

[0041] The countersink 157 is formed at a position corresponding to aneutral zone 155 which is a middle portion between the N pole and the Spole of the magnet 154. Thus, the countersink 157 provided at the loweryoke 151 and the countersunk head screw 158 inserted therein do notaffect a magnetic force of the magnet 157 attached to the lower surfaceof the upper yoke 152.

[0042] When the countersunk head screw 158 is inserted in thecountersink 157, the head of the countersunk head screw 158 does notprotrude above the upper surface of the lower yoke 151. This is toprevent the countersunk head screw 158 from interfering with the arm 146since the interval between the lower yoke 151 and the arm 146 is verysmall.

[0043] Boss insertion holes 165 are formed in each of the lower yoke 151and the upper yoke 152 respectively at both end portions in a lengthwisedirection. Bosses 120 protrude from the base plate 110 at a positioncorresponding to the boss insertion holes 165. The bosses 120 insertedin the boss insertion holes 165, prevent horizontal movements of thelower yoke 151 and the upper yoke 152. Also, each boss 120 functions asa standard in coupling the lower yoke 151 and the upper yoke 152 at anaccurate position.

[0044] A screw 159 is coupled to a screw coupling hole 114 formed ineach boss 120. Each boss 120 is formed higher than the height of thelower yoke 151 and lower than a sum of the heights of the lower yoke 151and the upper yoke 152. As a result, a coupling force of each screw 159is applied to the upper yoke 152 and the lower yoke 151 when the screws159 are coupled to each of the screw coupling holes 114.

[0045] The screws 159 are inserted in the boss insertion holes 165 in astate in which the upper yoke 152 is placed on the lower yoke 151 andcoupled to each of the screw coupling holes 114 provided in the boss120. Accordingly, the upper yoke 152 is fixedly coupled to the loweryoke 151. Simultaneously, the upper and lower yokes 152 and 151 can befirmly coupled to the base plate 110.

[0046] Since the base plate 110 is typically manufactured by aluminumdie casting, the upper surface thereof is not sufficiently flat. Thus,the entire lower surface of the lower yoke 151 may not directly contactwith the upper surface of the base plate 110. Accordingly, a firstsupport portion 122 having a predetermined height and a diameter greaterthan that of the lower end portion of the countersink 157 protrudesaround the screw coupling hole 112 where the countersunk head screw 158is coupled. Two second support portions 124 having a predeterminedheight and a diameter greater than that of the boss insertion holes 165protrude around the lower portion of each boss 120. In this case, theupper surfaces of the first and second support portions 122 and 124 arecut and processed to be flat and have the same height.

[0047] Thus, since the lower yoke 151 is supported at the first supportportion 122 and the plurality of second support portions 124 (at leastthree points in this instance), it can be stably supported at apredetermined distance from the base plate 110.

[0048] In addition, the hard disk drive comprises an actuator lockingapparatus 160. When the electric power of the hard disk drive is turnedoff, the actuator locking apparatus 160 locks the actuator 140 tomaintain a state in which the magnetic head 141 mounted on the actuator140 is parked in the parking zone of the disk. Thus, the actuatorlocking apparatus 160 prevents the actuator 140 from being moved to thedata zone out of the parking zone by unnecessarily pivoting due to anexternal impact during which the power is turned off and preventingpotential damage to the data zone and the magnetic head 141. If themagnetic head 141 is moved to the data zone in the power off state, themagnetic head 141 directly contacts the data zone and accordingly thedata zone and the magnetic head 141 may be damaged.

[0049] The actuator locking apparatus 160 locks the actuator 140 usingthe magnetic force of the magnet 154 attached to the lower surface ofthe upper yoke 152 of the voice coil motor 150. The actuator lockingapparatus 160 comprises a metal piece 163 installed at an end portion ofthe arm 146, a bending portion 166 provided at the upper yoke 152 andhaving a slot 167 having a predetermined width, and the lower surface ofthe bending portion 166 contacts with a contact portion 164 provided atthe lower yoke 151. The upper yoke 152 is magnetized by the magnet 153attached to the lower surface thereof. Accordingly, a magnetic fluxflows from the bending portion 166 of the upper yoke 152 toward thecontact portion 164 of the lower yoke 151. The magnetic flux leaks at aportion around the slot 167 and the metal piece 163 installed at the arm146 adheres to the bending portion 166 around the slot 167 by a leakagemagnetic flux.

[0050] In the actuator locking apparatus 160, the contact portion 164protrudes from the side surface of the lower yoke 151 and is bent suchthat the upper surface thereof is lower than the upper surface of thelower yoke 151 to reinforce the strength of a portion under the slot 167by increasing the height of the portion under the slot 167 of thebending portion 166. Accordingly, the portion under the slot 167 isprevented from being bent when the upper yoke 152 is-coupled to thelower yoke 151.

[0051] When the contact portion 164 is bent lower than the lower yoke151, the lower surface of the contact portion 164 interferes with theupper surface of the base plate 110 so that the lower yoke 151 is notinstalled horizontally on the base plate 110. Therefore, a recess 116having a predetermined depth may be formed in the upper surface of thebase plate 110 to prevent contact between the contact portion 164 andthe base plate 110. Accordingly, the lower yoke 151 can be stably fixedto the base plate 110.

[0052] As described above, in the voice coil motor coupling structure ofa hard disk drive according to the present invention, the lower yoke ofthe voice coil motor can be stably fixed at an accurate position notonly on a flat type base plate but also on a bowl type base plate. Also,the upper yoke can be easily coupled to the lower yoke.

[0053] Although a few embodiments of the present invention have beenshown and described, it would be appreciated by those skilled in the artthat changes may be made in this embodiment without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

What is claimed is:
 1. A voice coil motor coupling structure of a harddisk drive for coupling a voice coil motor to a base plate of the harddisk drive, the voice coil motor including a coil coupled to a rear endportion of an actuator arm, an upper yoke and a lower yoke provided atupper and lower portions of the coil, respectively, separated at apredetermined distance from the coil, and a magnet attached to the lowersurface of the upper yoke, the voice coil motor coupling structurecomprising: a countersink formed in the lower yoke; a countersunk headscrew inserted in the countersink and coupled to a screw coupling holeprovided in the base plate to fix the lower yoke to the base plate; bossinsertion holes formed in each of the lower and upper yokes respectivelyat both end portions in a lengthwise direction; bosses protruding fromthe base plate and inserted in the boss insertion holes; and screwsinserted in the boss insertion holes and coupled to respective screwcoupling holes provided at each boss, fixedly coupling the upper yoke tothe lower yoke.
 2. The voice coil motor coupling structure of claim 1,wherein the countersink is provided at a position corresponding to aneutral zone of the magnet.
 3. The voice coil motor coupling structureof claim 1, wherein, when the countersunk head screw is inserted in thecountersink, a head portion of the countersunk head screw does notprotrude above the upper surface of the lower yoke.
 4. The voice coilmotor coupling structure of claim 1, wherein the height of each boss isgreater than that of the lower yoke and less than a sum of the heightsof the lower yoke and the upper yoke.
 5. The voice coil motor couplingstructure of claim 1, further comprising a first support portionprotruding to a predetermined height and having a diameter greater thana lower end portion of the countersink and formed around the screwcoupling hole provided in the base plate, and a plurality of secondsupport portions, each protruding to a predetermined height and having adiameter greater than each of the boss insertion holes is formed arounda lower portion of each boss, so that the first and second supportportions support the lower yoke at a predetermined distance from thebase plate.
 6. The voice coil motor coupling structure of claim 5,wherein upper surfaces of the first and second support portions are flatand have the same height.
 7. The voice coil motor coupling structure ofclaim 1, further comprising: an actuator locking apparatus.
 8. The voicecoil motor coupling structure of claim 1, wherein the base plate is of abowl type.
 9. The voice coil motor coupling structure of claim 7,wherein the actuator locking apparatus comprises: a metal pieceinstalled at an end portion of the actuator arm; a bending portionprovided on the upper yoke; a slot provided on the bending portionhaving a predetermined width; and a contact portion provided on thelower yoke and bent such that an upper surface of the contact portion islower than an upper surface of the lower yoke.
 10. The voice coil motorcoupling structure of claim 9′, wherein a lower surface of the bendingportion contacts with the contact portion.
 11. The voice coil motorcoupling structure of claim 9, further comprising: a recess formed inthe base, plate, having a predetermined depth wherein the contactportion is inserted.
 12. A method of coupling a voice coil motor to abase plate of a hard disk drive, comprising: attaching a lower yoke of avoice coil motor to a base plate at a first point and a second point toprevent movement of the lower yoke relative to the base plate;assembling an arm of the voice coil motor to a pivot shaft; and couplingan upper yoke of the voice coil motor to the lower yoke of the voicecoil motor.
 13. The method of claim 12, wherein the attaching the loweryoke of the voice coil motor to the base plate, comprises: inserting acountersunk head screw into a countersink formed at the first point inthe lower yoke of the voice coil motor; and coupling the countersunkhead screw to a screw coupling hole at the first point.
 14. The methodof claim 12, wherein the coupling of the upper yoke of the voice coilmotor to the lower yoke of the voice coil motor, comprises: placing theupper yoke onto the lower yoke; coupling screws into boss insertionholes at both ends of the upper yoke and the lower yoke; and couplingthe screws into screw coupling holes respectively provided in each bosson the base plate of the hard disk drive.
 15. The method of claim 12,wherein the lower yoke is mounted on a boss at the second point.
 16. Themethod of claim 12, wherein the attaching the lower yoke of the voicecoil motor to the base plate at a first and a second point to preventmovement of the lower yoke relative to the base plate further comprises:a third point at which the lower yoke is mounted on a boss.
 17. A harddisk drive comprising: a voice coil motor having a coil coupled to arear end portion of an actuator arm; an upper yoke and a lower yokeprovided at upper and lower portions of the coil respectively, separatedat a predetermined distance from the coil; a magnet attached to thelower surface of the upper yoke; and a bowl-type base plate havingflattened structures at three points-for fastening the lower yoke in aposition relative to the bowl-type base plate prior to coupling theupper yoke to the lower yoke.
 18. The hard disk drive of claim 17,wherein the lower yoke is mounted on a screw coupling hole at a firstpoint and the lower yoke is mounted on a boss at each of a second andthird point.